Custom Patient-Specific 3D-Printed Titanium Truss Tibiotalocalcaneal Arthrodesis Implants for Failed Total Ankle Replacements: Classification, Technical Tips, and Treatment Algorithm.

BACKGROUND: The management of failed total ankle replacements, with significant loss of bone stock, is challenging with high rates of complications and associated morbidity. Recent technological advances have enabled the development of patient-customized 3D-printed titanium truss arthrodesis implants, which offer an alternative salvage option for failed total ankle replacements. METHODS: A prospective observational study was performed of 6 cases of failed total ankle replacements that were managed using custom patient-specific 3D-printed titanium truss arthrodesis implants. Technical tips, classification, and a treatment algorithm were developed based on our initial experience. RESULTS: Between November 2018 and March 2022, 6 patients underwent arthrodesis for failed total ankle replacements. Follow-up was available for all cases. The mean follow-up was 3.0 years (range 1-4.5). The mean MOXFQ Index improved from 73.1 to 32.3 (P < .05). The mean EQ-5D-5L Index improved from 0.366 to 0.743 (P < .05) and the EQ-VAS also improved from 53.0 to 63.3 (P = .36). The mean VAS-Pain score at final follow-up was 27.5. There were no cases of nonunion. None of the patients were smokers. The overall complication rate was 50%. Two patients returned to surgery: one for wound washout following TAR explantation and a second for removal of metalwork 2 years following surgery for a prosthetic joint infection secondary to hematogenous spread. No patients underwent revision fixation or amputation. CONCLUSION: Custom patient-specific 3D-printed titanium truss arthrodesis implants are a viable treatment option for failed total ankle replacements.

An In-Vitro Comparison of Mixed Reality Navigation to Traditional Freehand and Patient Specific Instrumentation Techniques for Glenoid Guide Pin Insertion during Shoulder Arthroplasty.

BACKGROUND: Accurate insertion of the glenoid guide pin in shoulder arthroplasty (RSA) is important for obtaining optimized glenoid component position and orientation. The objective of this study was to evaluate and compare the accuracy of three glenoid guide pin insertion techniques: 1) traditional software planning using freehand guide pin insertion (freehand), 2) guide pin insertion utilizing patient-specific instrumentation (PSI), and 3) using a mixed reality navigation (MR-NAV) system. METHODS: Twenty (20) computer tomography (CT) scans were obtained from patients exhibiting glenoid erosion patterns according to the Walch and Favard classifications. Cases were planned using validated three-dimensional (3D) preoperative planning software. The CT data was then used to 3D print triplicate plastic models of each glenoid to evaluate the three guide pin insertion techniques. The first technique employed traditional software planning with freehand guide pin insertion. The second method used preoperatively planned PSI guides, while the third utilized a MR-NAV system, which provided real-time holographic guidance during guide pin insertion. Once all guide pins had been inserted into the models, an independent optical tracking system and custom digitization device was used to quantify the position and orientation of each guide pin relative to the glenoid. The outcomes for this study included the absolute mean error in guide pin inclination, version, and entry point relative to the preoperative plan. The absolute Total Global Error was also assessed, which was defined as the sum of the absolute guide pin orientation and position error relative to the preoperative plan. RESULTS: No statistically significant differences between MR-NAV and PSI were found for the inclination error (2±1° versus 2±1°; P=0.056), version error (1±1° versus 1±1°; P=1.000), and Total Global Error (5±1 [mm+deg] versus 5±1 [mm+deg], P=1.000), respectively. The freehand technique produced significantly greater error than MR-NAV and PSI for inclination (5±3°, P≤0.017), version (4±3°, P≤0.032) and Total Global Error (8±3 [mm+deg], P<0.001). No statistically significant differences in the entry point error were observed between all guide pin insertion methods (P≥0.058). DISCUSSION: These results demonstrate that the precision and accuracy of MR-NAV is comparable to PSI and superior to a freehand technique for glenoid guide pin insertion in-vitro. Further study is needed to compare the accuracy of these techniques intra-operatively, in addition to assessing a potential learning curve between surgeons of varying experience with the MR-NAV system.

Three-dimensional planning, navigation, patient-specific instrumentation and mixed reality in shoulder arthroplasty: a digital orthopedic renaissance.

Accurate component placement in shoulder arthroplasty is crucial for avoiding complications, achieving superior biomechanical performance and optimizing functional outcomes. Shoulder and elbow surgeons have explored various methods to improve surgical understanding and precise execution including preoperative planning with 3D computed tomography (CT), patient-specific instrumentation (PSI), intraoperative navigation, and mixed reality (MR). 3D preoperative planning facilitated by CT scans and advanced software, enhances surgical precision, influences decision-making for implant types and approaches, reduces errors in guide pin placement, and contributes to cost-effectiveness. Navigation demonstrates benefits in reducing malpositioning, optimizing baseplate stability, improving humeral cut, and potentially conserving bone stock, although challenges such as varied operating times and costs warrant further investigation. The personalized patient care and enhanced operational efficiency associated with PSI are not only attractive for achieving desired component positions but also hold promise for improved outcomes in complex cases involving glenoid bone loss. Augmented reality (AR) and virtual reality (VR) technologies play a pivotal role in reshaping shoulder arthroplasty. They offer benefits in preoperative planning, intraoperative guidance, and interactive surgery. Studies demonstrate their effectiveness in AR-guided guidewire placement, providing real-time surgical advice during reverse total shoulder arthroplasty (RTSA). Additionally, these technologies show promise in orthopedic training, delivering superior realism and accelerating learning compared to conventional methods.

Comparison of 3D Computer Assisted Planning With and Without Patient Specific Instrumentation for Severe Bone Defects in Reverse Total Shoulder Arthroplasty.

BACKGROUND: Preoperative planning is an integral aspect of managing complex deformity in reverse shoulder arthroplasty (RSA). The purpose of this study was to compare the success of patient specific instrumentation (PSI) and 3D computer-assisted planning with standard instrumentation (Non-PSI) in achieving planned corrections of the glenoid among patients undergoing RSA with severe bony deformity requiring glenoid bone grafts. METHODS: A retrospective case-control study was performed, including all patients that underwent RSA with combined bone grafting procedures (BIO-RSA or structural bone grafting) for severe glenoid deformity by a single between June 2016 and July 2023. Patients were required to have preoperative and postoperative CT scans as well as preoperative 3D planning performed for inclusion. Patients were divided into two groups based on the use of 3D computer-assisted planning with or without PSI (PSI vs. Non-PSI). The corrected inclination and version were measured by two separate reviewers on preoperative and postoperative 2D CT scans and compared to their corresponding preoperative planning goals utilizing bivariate analyses. RESULTS: We identified 45 patients that met our inclusion criteria (22 PSI and 23 Non-PSI). Preoperative inclination (mean ± SD) (PSI 10.12° ± 15.86°, Non-PSI 9.43° ± 10.64°; P = 0.864) and version (PSI -18.78° ± 18.3°, Non-PSI -17.82° ± 11.49°; P = 0.835) measurements were similar between groups. No significant differences in the mean deviation (error) between the postoperative and planned inclination (PSI 5.49° ± 3.72; Non-PSI 6.91° ± 5.05; P = 0.437) and version (PSI 8.37° ± 5.7; Non-PSI 5.37° ± 4.43; P = 0.054) were found between groups. No difference in the rate of outliers (>10° error) was noted in inclination (P = 0.135) or version (P = 0.445) between groups. Greater planned version correction was correlated with greater error when PSI was utilized (PSI r = 0.519, P = 0.013; Non-PSI r = 0.362, P = 0.089). CONCLUSION: Both PSI and 3D computer-assisted planning without PSI (Non-PSI) appear to be useful techniques to achieve version and inclination correction among patients undergoing RSA with severe glenoid deformity required glenoid bone grafting with no clear superiority of one method over the other. Surgeons should be aware that when utilizing PSI, slightly greater error in achieving version goals may occur as version correction is increased.

Flexion contracture can cause component mismatch in the Prophecy® preoperative patient-specific instrumentation for Evolution® medial-pivot knee system.

INTRODUCTION: Patient-specific instrumentation (PSI) systems are used to conduct total knee arthroplasty. PSI reduces operative time, is less invasive and easier to use, and minimizes the risk of errors by providing precise measurements and reducing operating room turnover time. However, a study on the accuracy of Prophecy Evolution PSI (Microport Inc., Arlington, TN, USA) reported that 94% were below the error margin of 1.5 mm and 90% had error margins of 1 mm. This study aimed to evaluate the accuracy of the Prophecy Evolution PSI system in terms of the thickness of "total" bony resection required to achieve adequate extension/flexion gaps and the component match ratio between preoperative planning and actual component size inserted. METHODS: Comparisons were made between the sizes of femoral and tibial components planned with PSI and those inserted. The primary outcome was the average preoperative range of motion with and without matched femoral/tibial components. The study further analyzed the proportions of cases in which both the femoral and tibial components matched, neither matched, and only one of the femoral or tibial components matched. RESULTS: The ratio of the same sizes between the PSI planning and those inserted was 50.8% (33 patients) for both the femoral and tibial components. For the femoral component alone, the ratio was 84.6% (55 patients), and for the tibial component, it was 58.4% (38 patients). A receiver-operating characteristic curve analysis indicated that flexion contracture greater than 20° was a significant prognostic factor for the PSI component match group versus the mismatch group. DISCUSSION: Flexion contracture may cause PSI mismatch. Notably, flexion contracture greater than 20° was a significant risk factor for the PSI component match group versus the mismatch group. During preoperative planning for a patient with flexion contracture, surgeons should prepare for the possibility of inserting an undersized tibial component.

The influence of the weight-bearing state on three-dimensional (3D) planning in lower extremity realignment - analysis of novel vs. state-of-the-art planning approaches.

BACKGROUND: The use of 3D planning to guide corrective osteotomies of the lower extremity is increasing in clinical practice. The use of computer-tomography (CT) data acquired in supine position neglects the weight-bearing (WB) state and the gold standard in 3D planning involves the manual adaption of the surgical plan after considering the WB state in long-leg radiographs (LLR). However, this process is subjective and dependent on the surgeons experience. A more standardized and automated method could reduce variability and decrease costs. PURPOSE: The aim of the study was (1) to compare three different three-dimensional (3D) planning modalities for medial open-wedge high tibial osteotomy (MOWHTO) and (2) to describe the current practice of adapting NWB CT data after considering the WB state in LLR. The purpose of this study is to validate a new, standardized approach to include the WB state into the 3D planning and to compare this method against the current gold standard of 3D planning. Our hypothesis is that the correction is comparable to the gold standard, but shows less variability due compared to the more subjective hybrid approach. METHODS: Three surgical planning modalities were retrospectively analyzed in 43 legs scheduled for MOWHTO between 2015 and 2019. The planning modalities included: (1) 3D hybrid (3D non-weight-bearing (NWB) CT models after manual adaption of the opening angle considering the WB state in LLR, (2) 3D NWB (3D NWB CT models) and (3) 3D WB (2D/3D registration of 3D NWB CT models onto LLR to simulate the WB state). The pre- and postoperative hip-knee-ankle angle (HKA) and the planned opening angle (°) were assessed and differences among modalities reported. The relationship between the reported differences and BMI, preoperative HKA (LLR), medial meniscus extrusion, Outerbridge osteoarthritis grade and joint line convergence angle (JLCA) was analyzed. RESULTS: The mean (std) planned opening angle of 3D hybrid did not differ between 3D hybrid and 3D WB (0.4 ± 2.1°) (n.s.) but was higher in 3D hybrid compared to 3D NWB (1.1° ± 1.1°) (p = 0.039). 3D WB demonstrated increased preoperative varus deformity compared to 3D NWB: 6.7 ± 3.8° vs. 5.6 ± 2.7° (p = 0.029). Patients with an increased varus deformity in 3D WB compared to 3D NWB (> 2 °) demonstrated more extensive varus alignment in LLR (p = 0.009) and a higher JLCA (p = 0.013). CONCLUSION: Small intermodal differences between the current practice of the reported 3D hybrid planning modality and a 3D WB approach using a 2D/3D registration algorithm were reported. In contrast, neglecting the WB state underestimates preoperative varus deformity and results in a smaller planned opening angle. This leads to potential under correction in MOWHTO, especially in patients with extensive varus deformities or JLCA. CLINICAL RELEVANCE: Incorporating the WB state in 3D planning modalities has the potential to increase accuracy and lead to a more consistent and reliable planning in MOWHTO. The inclusion of the WB state in automatized surgical planning algorithms has the potential to reduce costs and time in the future.

Artificial intelligence- and computer-assisted navigation for shoulder surgery.

Background: Over the last few decades, shoulder surgery has undergone rapid advancements, with ongoing exploration and the development of innovative technological approaches. In the coming years, technologies such as robot-assisted surgeries, virtual reality, artificial intelligence, patient-specific instrumentation, and different innovative perioperative and preoperative planning tools will continue to fuel a revolution in the medical field, thereby pushing it toward new frontiers and unprecedented advancements. In relation to this, shoulder surgery will experience significant breakthroughs. Main body: Recent advancements and technological innovations in the field were comprehensively analyzed. We aimed to provide a detailed overview of the current landscape, emphasizing the roles of technologies. Computer-assisted surgery utilizing robotic- or image-guided technologies is widely adopted in various orthopedic specialties. The most advanced components of computer-assisted surgery are navigation and robotic systems, with functions and applications that are continuously expanding. Surgical navigation requires a visual system that presents real-time positional data on surgical instruments or implants in relation to the target bone, displayed on a computer monitor. There are three primary categories of surgical planning that utilize navigation systems. The initial category involves volumetric images, such as ultrasound echogram, computed tomography, and magnetic resonance images. The second type is based on intraoperative fluoroscopic images, and the third type incorporates kinetic information about joints or morphometric data about the target bones acquired intraoperatively. Conclusion: The rapid integration of artificial intelligence and deep learning into the medical domain has a significant and transformative influence. Numerous studies utilizing deep learning-based diagnostics in orthopedics have remarkable achievements and performance.

The feasibility of a novel 3D-Printed patient specific cutting guide for extended trochanteric osteotomies.

BACKGROUND: The extended trochanteric osteotomy (ETO) is a surgical technique utilized to expose the intramedullary canal of the proximal femur, protect the soft tissues and promote reliable healing. However, imprecise execution of the osteotomy can lead to fracture, soft tissue injury, non-union, and unnecessary morbidity. We developed a technique to create patient specific, 3D-printed cutting guides to aid in accurate positioning of the ETO and improve osteotomy quality and outcomes. METHODS: Patient specific cutting guides were created based on CT scans using Synopysis Simpleware ScanIP and Solidworks. Custom 3D printed cutting guides were tested on synthetic femurs with foam cortical shells and on cadaveric femurs. To confirm accuracy of the osteotomies, dimensions of the performed osteotomies were compared to the virtually planned osteotomies. RESULTS: Use of the patient specific ETO cutting guides resulted in successful osteotomies, exposing the femoral canal and the femoral stem both in synthetic sawbone and cadaveric testing. In cadaveric testing, the guides allowed for osteotomies without fracture and cuts made using the guide were accurate within 6 percent error from the virtually planned osteotomy. CONCLUSION: The 3D-printed patient specific cutting guides used to aid in ETOs proved to be accurate. Through the iterative development of cutting guides, we found that a simple design was key to a reliable and accurate guide. While future clinical trials in human subjects are needed, we believe our custom 3D printed cutting guide design to be effective at aiding in performing ETOs for revision total hip arthroplasty surgeries.

Higher satisfaction and function scores in restricted kinematic alignment versus mechanical alignment with medial pivot design total knee arthroplasty: A prospective randomised controlled trial.

PURPOSE: Restricted kinematic alignment (rKA) in total knee arthroplasty (TKA) and medial pivot (MP) knee designs already showed superior outcomes in independent comparative studies. The objective of this study was to assess whether rKA with MP TKA provides better clinical and functional outcomes compared to mechanical alignment (MA) with MP TKA. METHODS: This is a randomised, parallel two group study involving a total of 98 patients with end-stage knee osteoarthritis. Patients were randomly allocated to either rKA or MA TKA procedures conducted with a MP prothesis using patient-specific instruments between 2017 and 2020. Final follow-up was at 2 years postoperatively. Demographic data and clinical and functional scores (Oxford knee score, knee society score [KSS], Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], forgotten joint score [FJS]) were collected and compared preoperative, 1 year postoperative and 2 years postoperative. Coronal plane alignment of the knee and functional knee phenotype classification were recorded. RESULTS: A total of 47 patients (rKA) and 51 patients (MA) were included in final analysis. Superior joint awareness scores (FJS) were found at 1 year postoperative for rKA (62.2 vs. 52.4, p = 0.04). KSS subscores (expectation score, satisfaction score) improved with rKA with significant differences at both 1 and 2 years postoperatively. Major differences between rKA and MA were found in subgroup analysis of varus and neutral CPAK phenotypes. Both 1 year and 2 years postoperatively, FJS was significantly better in KA compared with MA in varus CPAK phenotypes (63.1 vs. 44.9, p = 0.03; 71.1 vs. 46.0, p = 0.005). Further clinical and functional scores showed improvement in the varus CPAK phenotypes with predominantly significant improvement in the expectation and satisfaction KSS subscores. No significant differences were found in the comparison of rKA and MA in neutral CPAK phenotypes. CONCLUSION: The rKA of MP TKA design shows superior patient satisfaction and self-reported function when compared to MA MP TKA. Furthermore, rKA MP TKA shows superior joint awareness at early postoperative stage. The most important clinical relevance of this study is the clear superiority of rKA in varus phenotypes. LEVEL OF EVIDENCE: Level II.

Using a patient-specific cutting guide enables identical knee osteotomies: An evaluation of accuracy on sawbones.

PURPOSE: It was hypothesized that using a Patient-Specific Cutting Guide (PSCG) would allow the creation of sawbones model osteotomies, identical in the 3 planes and the hinge parameters, that can be used for biomechanical studies. The aim of the study was to evaluate the accuracy of the PSCG system and to introduce and assess the new hinge parameter; the hinge area. METHODS: Six identical sawbones tibia models were identically set up for identical osteotomy cuts by the same surgeon in the same session and with identical instruments. A medical scanner was used to evaluate the 3D configuration of all the specimens. The analyzed parameters included the cutting angles in both the coronal and sagittal planes (degrees) and the hinge and the slicing areas (cm2), and the hinge thickness (mm). The values were statistically evaluated for average, standard deviation, 95% confidence index, and delta to the expected values were calculated. RESULTS: The mean values for the coronal and sagittal angles were 110.5̊±1̊ and 89.8̊±0.8̊, respectively. The 95% confidence index level ranged between 0.1̊, and 0.8̊ in both the coronal & the sagittal planes. The mean values for the hinge thickness, the hinge area, and the slicing area were 12.7±1.5mm, 4.2±0.9 cm2, and 18.3±1.2 cm2, respectively. CONCLUSION: In the presented study, it can be demonstrated that mechanically identical osteotomy specimens, with regard to the cutting planes and hinge parameters, can be reliably created using the PSCG. The identical specimens can be used for biomechanical research purposes to further expand our knowledge of the factors affecting osteotomy outcomes. LEVEL OF EVIDENCE: IV.

Femoral head allograft for glenoid bone loss in primary reverse shoulder arthroplasty: functional and radiologic outcomes.

BACKGROUND: Several techniques have been adopted during primary reverse shoulder arthroplasty (RSA) to manage glenoid bone defect. Among bone grafts, humeral head autograft is currently the mainstream option. However, autologous humeral heads may be unavailable or inadequate, and allografts may be a viable alternative. The aim of the present study was to evaluate the functional and radiologic outcomes of femoral head allografts for glenoid bone defects in primary RSA. METHODS: We conducted a retrospective study with prospective data collection enrolling 20 consecutive patients who underwent RSA with femoral head allografts for glenoid bone defects. Indications for surgery were eccentric cuff tear arthropathy in 10 cases (50%), concentric osteoarthritis in 9 cases (45%), and fracture sequelae in 1 case (5%). Each patient was evaluated preoperatively and at follow-up by radiologic and computed tomography (CT) and by assessing the range of motion (ROM) and the Constant-Murley score (CMS). A CT-based software, a patient-specific 3D model of the scapula, and patient-specific instrumentation were used to shape the graft and to assess the position of K-wire for the central peg. Postoperatively, CT scans were used to identify graft incorporation and resorption. RESULTS: After a median follow-up of 26.5 months (24-38), ROM and CMS showed a statistically significant improvement (all P = .001). The median measures of the graft were as follows: 28 mm (28-29) for diameter, 22° (10°-31°) for angle, 4 mm (2-8 mm) for minimum thickness, and 15 mm (11-21 mm) for maximum thickness. Before the surgery, the median glenoid version was 21.8° (16.5°-33.5°) for the retroverted glenoids and -13.5° (-23° to -12°) for the anteverted glenoids. At the follow-up, the median postoperative baseplate retroversion was 5.7° (2.2°-1.5°) (P = .001), and this value was close to the 4° retroversion planned on the preoperative CT-based software. Postoperative major complications were noted in 4 patients: 2 dislocations, 1 baseplate failure following a high-energy trauma, and 1 septic baseplate failure. Partial graft resorption without glenoid component failure was observed in 3 cases that did not require revision surgery. CONCLUSION: The femoral head allograft for glenoid bone loss in primary RSA restores shoulder function, with CMS values comparable to those of sex- and age-matched healthy individuals. A high rate of incorporation of the graft and satisfactory correction of the glenoid version can be expected after surgery. The management of glenoid bone defects remains a challenging procedure, and a 15% risk of major complication must be considered.

Custom-made total ankle arthroplasty with patient-specific instrumentation for severe bone loss conditions: a case series.

PURPOSE: Management of bone loss around the ankle is a challenging condition. This retrospective study describes the design process, the surgical technique, and the preliminary results of custom-made total ankle arthroplasties (TAA) with patient-specific instrumentation (PSI) for different severe bone loss conditions. METHODS: Consecutive patients that underwent custom-made TAA for severe bone loss conditions were included. The primary outcome was to describe the implant design in relation to the bone defect. Moreover, pre-operative and final follow-up clinical scores were compared. RESULTS: Seven patients were included. Post-operative radiographs showed good correspondence between the pre-operative planning and the prosthesis alignment in all patients. Improvement in clinical scores was observed in all patients at the final follow-up. One patient developed a deep infection. CONCLUSION: Short-term results reported herein are encouraging suggesting that custom-made TAA implants with PSI may represent an effective solution for ankle bone loss conditions.

Patient-Reported Outcomes in Total Ankle Arthroplasty: Patient Specific Versus Standard Instrumentation.

BACKGROUND: Total ankle arthroplasty (TAA) can now be performed using patient-specific instrumentation (PSI). Advantages include the ability to preoperatively plan and reduce the number of intraoperative surgical steps. The aim of this study was to compare PSI with standard instrumentation (SI) in a nonrandomized retrospective cohort study with respect to patient-reported outcome measures (PROMs). Secondary aims were to compare complications, reoperations, tourniquet time, fluoroscopy time, and postoperative alignment. METHODS: In all, 159 patients (111 men, 48 women) undergoing a total of 168 Infinity TAA (Stryker, Memphis, TN) using PSI (Prophecy, Stryker, Memphis, TN) or SI between 2014 and 2021 were included with a minimum follow-up of 12 months. The PROMs were obtained preoperatively and at 1 year, and included the Manchester-Oxford Foot Questionnaire (MOXFQ), Ankle Osteoarthritis Scale (AOS), and European Quality of Life 5 Dimension 3 Level (EQ-5D-3L). Coronal plane deformity correction was assessed using the midline tibiotalar angle (MTTA). Demographics, tourniquet time, and intraoperative fluoroscopy times were obtained from the hospital records. RESULTS: There were 61 TAAs in the PSI group and 107 TAAs in the SI group. There was no significant difference in total MOXFQ, AOS, or EQ-5D. There was a significantly reduced tourniquet time (PSI mean: 95.39 minutes, SI mean: 116.87 minutes, P < .001) and radiation exposure (PSI mean: 31 seconds, SI mean: 53 seconds, P < .001). Angular correction was more accurate in the PSI group (PSI mean: 1.29°, SI mean: 2.26°, P = .005). CONCLUSION: This study supports the use of PSI to decrease operative time, reduce intraoperative fluoroscopy, improve accuracy of implantation, and improve postoperative alignment in TAA. There was a significant difference (P = .032) in favor of PSI in the walking/standing domain of the MOXFQ at 12 months but no significant difference in overall PROMs. LEVELS OF EVIDENCE: Level III, Retrospective.

3-dimensionally printed patient-specific glenoid drill guides vs. standard nonspecific instrumentation: a randomized controlled trial comparing the accuracy of glenoid component placement in anatomic total shoulder arthroplasty.

BACKGROUND: Traditional, commercially sourced patient-specific instrumentation (PSI) systems for shoulder arthroplasty improve glenoid component placement but can involve considerable cost and outsourcing delays. The purpose of this randomized controlled trial was to compare the accuracy of glenoid component positioning in anatomic total shoulder arthroplasty (aTSA) using an in-house, point-of-care, 3-dimensionally (3D) printed patient-specific glenoid drill guide vs. standard nonspecific instrumentation. METHODS: This single-center randomized controlled trial included 36 adult patients undergoing primary aTSA. Patients were blinded and randomized 1:1 to either the PSI or the standard aTSA guide groups. The primary endpoint was the accuracy of glenoid component placement (version and inclination), which was determined using a metal-suppression computed tomography scan taken between 6 weeks and 1 year postoperatively. Deviation from the preoperative 3D templating plan was calculated for each patient. Blinded postoperative computed tomography measurements were performed by a fellowship-trained shoulder surgeon and a musculoskeletal radiologist. RESULTS: Nineteen patients were randomized to the patient-specific glenoid drill guide group, and 17 patients were allocated to the standard instrumentation control group. There were no significant differences between the 2 groups for native version (P = .527) or inclination (P = .415). The version correction was similar between the 2 groups (P = .551), and the PSI group was significantly more accurate when correcting version than the control group (P = .042). The PSI group required a significantly greater inclination correction than the control group (P = .002); however, the 2 groups still had similar accuracy when correcting inclination (P = .851). For the PSI group, there was no correlation between the accuracy of component placement and native version, native inclination, or the Walch classification of glenoid wear (P > .05). For the control group, accuracy when correcting version was inversely correlated with native version (P = .033), but accuracy was not correlated with native inclination or the Walch classification of glenoid wear (P > .05). The intraclass correlation coefficient was 0.703 and 0.848 when measuring version and inclination accuracy, respectively. CONCLUSION: When compared with standard instrumentation, the use of in-house, 3D printed, patient-specific glenoid drill guides during aTSA led to more accurate glenoid component version correction and similarly accurate inclination correction. Additional research should examine the influence of proper component position and use of PSI on clinical outcomes.

Technology assistance in primary total knee replacement: hype or hope?

INTRODUCTION: Total knee replacement (TKR) reduces pain, it increases quality of life and it generally lasts a long time with revision rates of less than 5% at 10 years. Some authors have suggested that outcomes may be further improved by technology assistance. AREAS COVERED: Technology assistance in primary TKR includes technologies such as navigated TKR, patient specific instrumentation TKR and robotic TKR. EXPERT OPINION: In general, technology assistance results in higher accuracy of component positioning and alignment, but this is likely not clinically relevant as no clinically important difference in clinical outcomes, quality of life and complications such as revisions has been demonstrated in meta-analyses of randomized controlled trials. As technology assistance in primary TKR is increasingly used to capture patient and surgeon data, surgeons have an increasingly important role in protecting their patients' data and their own data. Real world evidence of implant registries has shown that TKR without technologically assistance can achieve perfectly acceptable outcomes. Although there is a genuine hope that technology-assisted TKR may further improve these outcomes, this hope is based on promises rather than solid evidence. At the same time, technology assisted TKR is heavily promoted including direct patient marketing, which are aspects of a hype.

Acetabular cup positioning in primary routine total hip arthroplasty-a review of current concepts and technologies.

INTRODUCTION: Total hip arthroplasty (THA) has revolutionized the treatment of hip joint arthritis. With the increased popularity and success of the procedure, research has focused on improving implant survival and reducing surgical complications. Optimal component orientation has been a constant focus with various philosophies proposed. Regardless of the philosophy, achieving an accurate acetabular position for each clinical scenario is crucial. In this paper, we review the recent developments in improving the accuracy and ideal positioning of the acetabular cup in routine primary THA. METHODOLOGY: A review of the recent scientific literature for acetabular cup placement in primary THA was performed, with available evidence for safe zones, spinopelvic relationship, preoperative planning, patient-specific instrumentation, navigation THA and robotic THA. CONCLUSION: Though the applicability of Lewinnek safe zones has been questioned with an improved understanding of spinopelvic relationships, its role remains in positioning the acetabular cup in a patient with normal spinopelvic alignment and mobility. Evaluation of spinopelvic relationships and accordingly adjusting acetabular anteversion and inclination can significantly reduce the incidence of dislocation in patients with a rigid spine. In using preoperative radiography, the acetabular inclination, anteversion and intraoperative pelvic position should be evaluated. With improving technology and the advent of artificial intelligence, superior and more accurate preoperative planning is possible. Patient-specific instrumentation, navigated and robotic THA have been reported to improve accuracy in acetabular cup positioning as decided preoperatively but any significant clinical advantage over conventional THA is yet to be elucidated.

Computed tomography-based patient-specific cutting guides used for positioning of the femoral component of implants during unicompartmental knee arthroplasty: a cadaver study.

BACKGROUND: To investigate whether patient-specific instrumentation (PSI) improves the femoral component positioning of implants during unicompartmental knee arthroplasty (UKA) using cadaver bone models. METHODS: Fifty adult cadaveric femoral bone specimens collected from February 2016-2018, were randomized to receive medial UKA with a PSI guide (n = 25) or conventional instrumentation (CI) (n = 25). Standard anteroposterior and lateral view radiographs were obtained postoperatively to assess the coronal and sagittal positioning of the femoral prostheses, respectively. The osteotomy time was recorded to assess the convenience of PSI in guiding osteotomy. RESULTS: Osteotomy time significantly shortened in the PSI group (3.12 ± 0.65 versus 4.33 ± 0.73 min, p < 0.001). There was a significant difference in the postoperative coronal alignment of the femoral component between the PSI and CI groups (varus/valgus angle: 1.43 ± 0.93° vs. 2.65 ± 1.50°, p = 0.001). The prevalence of outliers in coronal alignment was lower in the PSI than the CI group (2/25, 8% vs. 9/25, 36%). Sagittal posterior slope angle of the femoral component was significantly different between the two groups (8.80 ± 0.65° and 6.29 ± 1.88° in the CI and PSI groups, respectively, p < 0.001). The malalignment rate of the femoral component in the sagittal plane was 60% in the CI group, whereas no positioning deviation was observed in the PSI group. CONCLUSION: This study used a cadaver model to support the fact that CT-based PSI shows an advantage over CI in optimizing implant positioning for UKAs.

Development and Validation of an Artificial Intelligence Preoperative Planning and Patient-Specific Instrumentation System for Total Knee Arthroplasty.

BACKGROUND: Accurate preoperative planning for total knee arthroplasty (TKA) is crucial. Computed tomography (CT)-based preoperative planning offers more comprehensive information and can also be used to design patient-specific instrumentation (PSI), but it requires well-reconstructed and segmented images, and the process is complex and time-consuming. This study aimed to develop an artificial intelligence (AI) preoperative planning and PSI system for TKA and to validate its time savings and accuracy in clinical applications. METHODS: The 3D-UNet and modified HRNet neural network structures were used to develop the AI preoperative planning and PSI system (AIJOINT). Forty-two patients who were scheduled for TKA underwent both AI and manual CT processing and planning for component sizing, 20 of whom had their PSIs designed and applied intraoperatively. The time consumed and the size and orientation of the postoperative component were recorded. RESULTS: The Dice similarity coefficient (DSC) and loss function indicated excellent performance of the neural network structure in CT image segmentation. AIJOINT was faster than conventional methods for CT segmentation (3.74 ± 0.82 vs. 128.88 ± 17.31 min, p < 0.05) and PSI design (35.10 ± 3.98 vs. 159.52 ± 17.14 min, p < 0.05) without increasing the time for size planning. The accuracy of AIJOINT in planning the size of both femoral and tibial components was 92.9%, while the accuracy of the conventional method in planning the size of the femoral and tibial components was 42.9% and 47.6%, respectively (p < 0.05). In addition, AI-based PSI improved the accuracy of the hip-knee-ankle angle and reduced postoperative blood loss (p < 0.05). CONCLUSION: AIJOINT significantly reduces the time needed for CT processing and PSI design without increasing the time for size planning, accurately predicts the component size, and improves the accuracy of lower limb alignment in TKA patients, providing a meaningful supplement to the application of AI in orthopaedics.

Computer aided multiplanar osteotomy using patient specific instrumentation to treat cubitus varus in children.

Cubitus varus deformity is a common complication of supracondylar fractures in children. Anatomic correction is the key to obtaining good functional results and avoiding later symptomatic degradation. Different techniques have been described, mainly lateral closing wedge osteotomy. A medial opening wedge osteotomy seems more intuitive, allowing an anatomic reduction, but it is technically challenging. Two-plane radiographs are too simplistic to appreciate the 3D deformity. With medical imaging and image processing advances, three-dimensional (3D) virtual models of a patient's anatomy can be generated. Rapid 3D printing has allowed virtual simulations of surgical corrections to be transferred to real-world applications in the operating room, allowing more precise and accurate surgery with better 3D corrections. 3D computer modeling with the development of customized drilling and cutting guides allows complex medial opening wedge osteotomy for correction of cubitus varus deformity in immature children with best-fit plate synthesis. LEVEL OF EVIDENCE: IV.

Computer-assisted planning vs. conventional surgery for the correction of symptomatic mid-shaft clavicular nonunion and malunion.

Background: The aim of this study was to compare the clinical and radiographic outcomes of treatment of symptomatic mal- and/or nonunion of midshaft clavicle fractures using radiographically based free-hand open reduction and internal fixation (ORIF) or computer-assisted 3D-planned, personalized corrective osteotomies performed using patient-specific instrumentation (PSI) and ORIF. The hypotheses were that (1) patients treated with computer-assisted planning and PSI would have a better clinical outcome, and (2) computer-assisted surgical planning would achieve a more accurate restoration of anatomy compared to the free-hand technique. Methods: Between 1998 and 2020, 13 patients underwent PSI, and 34 patients underwent free-hand ORIF and/or corrective osteotomy. After application of exclusion criteria, 12/13 and 11/34 patients were included in the study. The clinical examination included measurement of the active range of motion and assessment of the absolute and relative Constant-Murley Scores and the subjective shoulder value. Subjective satisfaction with the cosmetic result was assessed on a Likert scale from 0 to 100 (subjective aesthetic value). 11/13 and 6/11 patients underwent postoperative computed tomography evaluation of both clavicles. Computed tomography scans were segmented to generate 3D surface models. After projection onto the mirrored contralateral side, displacement analysis was performed. Finally, bony union was documented. The average follow-up time was 43 months in the PSI and 50 months in the free-hand cohort. Results: The clinical outcomes of both groups did not differ significantly. Median subjective shoulder value was 97.5% (70; 100) in the PSI group vs. 90% (0; 100) in the free-hand group; subjective aesthetic value was 86.4% (±10.7) vs. 75% (±18.7); aCS was 82.3 (±10.3) points vs. 74.9 (±26) points; and rCS was 86.7 (±11.3) points vs. 81.9 (±28.1) points. In the free-hand group, 2/11 patients had a postoperative neurological complication. In the PSI cohort, the 3D angle deviation was significantly smaller (PSI/planned vs. free-hand/contralateral: 10.8° (3.1; 23.8) vs. 17.4° (11.6; 42.4); P = .020)). There was also a trend toward a smaller 3D shift, which was not statistically significant (PSI/planned vs. free-hand/contralateral: 6 mm (3.4; 18.3) vs. 9.3 mm (5.1; 18.1); P = .342). There were no other significant differences. A bony union was achieved in all cases. Conclusion: Surgical treatment of nonunion and malunions of the clavicle was associated with very good clinical results and a 100% union rate. This study, albeit in a relatively small cohort with a follow-up of 4 years, could not document any clinically relevant advantage of 3D planning and personalized operative templating over conventional radiographic planning and free-hand surgical fixation performed by experienced surgeons.